This invention relates to an electric drip coffeemaker hot water generator and, more particularly, to an improved method of joining and sealing a wrought aluminum cover to a diecast aluminum hot water generator.
2. Description of the Prior Art and Cross Reference to a Related Application
In a co-pending application of Robert L. Schaeffer, Ser. No. 06/657,349, filed Oct. 3, 1984, now U.S. Pat. No. 4,546,697 and assigned to the same assignee as the present invention, there is disclosed a hot water generator for an electric drip coffeemaker. The hot water generator includes an aluminum die casting having a "U" shaped hot water channel with the bottom and side walls of the hot water channel formed in the casting. A generally "U" shaped aluminum cover is positioned on top of the casting for forming the top wall of the "U" shaped hot water channel.
Automatic welding of any type is not normally used as a suitable joining method for aluminum die castings and wrought aluminum particularly when a water tight seal is required. Die castings present a problem in welding because small pockets of gas are trapped in the metal during the casting process and when the metal fuses during welding, these pockets expand and migrate through the weld. This porosity can be connected and thus the weld is not sealed. In extreme cases where a relatively large pocket of gas exists, it can even blow a hole completely through the weld, thus creating a major leak. It is very desirable to be able to automatically weld a wrought aluminum cover to a drip coffeemaker hot water generator aluminum die casting in a high speed automatic manufacturing process.